Field of the Invention
The present invention relates to a pouch type secondary battery and a method of manufacturing the same.
Description of the Related Art
As the technical development and the demand on mobile devices increase, the demand on secondary batteries as energy sources rapidly increases. Thus, researches on batteries meeting diverse demands have been conducted substantially. Particularly, rechargeable secondary batteries receive attention as power sources of electric vehicles, hybrid electric vehicles, etc.
Secondary batteries may be manufactured in a variety of forms. Typically, demands on a prismatic type secondary battery and a pouch type secondary battery, having a thin thickness and applicable in products such as a cellular phone are high. When considering materials, demands on a lithium secondary battery such as a lithium cobalt polymer battery having good energy density, discharge voltage and safety are high.
Among the above-described batteries, the pouch type secondary battery is favorable for realizing the slimness and lightweight of portable electronic devices.
The pouch type secondary battery is manufactured by receiving an electrode assembly including a cathode, an anode and a separator in a pouch type case of an exterior material, performing a first formation of a battery, degassing using an extra part, cutting and removing the extra part, and performing a second formation of the battery.
In this case, the safety of the battery may be deteriorated due to the current flowing through an exposed metal layer of the pouch type case by the cutting, and water permeation and electrolyte loss may be generated by the loss of packaging capability due to corrosion. Particularly, side reactions in the battery due to water may be generated, and battery performance and safety may be deteriorated.
Therefore, a method of manufacturing a pouch type secondary battery that may improve the above-described defects is greatly required.